Thermal regeneration has been proposed for increasing the thermal efficiency of an internal combustion engine. Thermal regeneration consists of the introduction of a heat exchanger within the cylinder which has a core made from a material capable of withstanding nigh temperatures while exhibiting low thermal conductivity. During the exhaust cycle of the engine, the core absorbs the exhaust gas heat. The exhaust gas heat is then transferred from the core to the working fluid following the compression cycle, but prior to or during the combustion of fuel, in order to reduce the required quantity of fuel to be burned.
A regenerative internal combustion engine is disclosed in U.S. Pat. No. 4,790,284 issued to Allan J. Ferrenberg et. al. on Dec. 13, 1988 wherein a regenerator captures the unutilized heat normally expelled with the exhaust products of an engine and transfers it to the fresh working fluid at the appropriate time in the next engine operating cycle to reduce the quantity of fuel which must be burned such as that described above. This is accomplished through the use of a permeable, movable heat exchanger located between the piston and the cylinder head. However, the quantity of heat which can be recirculated in this way corresponds to the cooling from the temperature of the exhaust gas after expansion to the temperature of the compressed gas late in the compression process. Therefore, when the gas is compressed isentropically, its end-of-compression temperature is high which limits the efficacy of the regenerator in the disclosed patent.
The present invention is directed at overcoming the problems as set forth above.